The purpose of this grant is to obtain a state-of-the-art system for recording horizontal and vertical eye position, for recording the accommodative state of the lens of the eye, and for stabilizing the image of a visual stimulus on the retina. This integrated recording system, manufactured by SRI International, is unique among currently available systems in providing extremely high recording accuracy and low noise without rigid head restraint and with no attachments to the subject's eye or head. As a result, data can be obtained from a wide variety of subjects, including patients who are undergoing evaluation and treatment for oculomotor anomalies. Although the cost of the apparatus makes it difficult to justify for any individual investigator, it will significantly enhance the research of each by permitting observations and experiments not possible without it, and by improving the quality of observations that would otherwise be made. As a shared resource, the system will be used by a major user group of six investigators holding R01 grants from NIH. Each investigator has detailed a plan of research that enhances or extends their research projects. These include the following specific aims: (a) to measure transfer functions for the distal visual system with compensation for the effects of eye movements; (b) to examine the accuracy and stimulus-dependent limitations on the programming of saccadic and vergence eye movements; (c) to determine if eye movements and variations in stimulus fixation affect the components of the averaged visual evoked potential; (d) to study the processes of light adaptation and the perception of visual direction; (e) to examine in detail the characteristics of oculomotor control in patients with various ocular disorders; and (f) to record fixations of text as a measure of word recognition and lexical influence on the parsing of sentences. In addition to these projects outlined by the major user group, the SRI system will attract investigators from other departments in the University (e.g., Computer Science) and from other Universities in the Rochester area (e.g., Cornell).